Abstract

The process of fertigation, which consists in providing plants with minerals contained in irrigation water, is widespread, despite a number of negative effects. The overwhelming majority of studies are aimed at studying the spatial distribution of salts during irrigation; in interirrigation periods and at the end of the irrigation season, the processes of salt migration and concentration in soil under conditions of reduced moisture (drying conditions) are hardly covered by studies. The purpose of this research is to model the drying regimes of light and dark gray forest soils in the Chuvash Republic (Russia) after fertigation. The studies were carried out from 2020 to 2023. Since the state of soil prior to drip irrigation significantly influences the drying process, the paper considers situations that make it possible to reduce the negative effects of this process. Modeling of the movement of soil moisture during and after the end of drip irrigation makes it possible to identify different cases of the formation of a salt “fringe.” The identification of such regimes makes it possible to preliminarily prepare the soil for fertigation, taking into account the features of the initial distribution of moisture. This paper shows that salts can concentrate mainly in areas with a sharp moisture gradient, i.e., at the boundaries between dry and moist soil, during drying. This is explained by the fact that soil moisture enters an area with an already increased salt concentration due to the resulting pressure drop. The developed model makes it possible to analyze the effect of salt fringe formation according to the set initial and boundary conditions in the form of moisture gradients, porosity, specific soil surface, irrigation intensity and duration, and salt concentration.

中文翻译：

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滴灌期间“盐边”出现的模拟机制

摘要

尽管有许多负面影响，但灌溉施肥过程为植物提供灌溉水中所含的矿物质，这一过程很普遍。绝大多数研究旨在研究灌溉过程中盐分的空间分布；在灌溉期间和灌溉季节结束时，在水分减少（干燥条件）的条件下盐分在土壤中的迁移和浓缩过程几乎没有被研究涵盖。本研究的目的是模拟楚瓦什共和国（俄罗斯）施肥后浅灰色和深灰色森林土壤的干燥状况。该研究于 2020 年至 2023 年进行。由于滴灌前的土壤状态显着影响干燥过程，因此本文考虑了可以减少该过程负面影响的情况。对滴灌期间和结束后土壤水分运动进行建模，可以识别盐“边缘”形成的不同情况。考虑到水分初始分布的特征，识别这种状态使得可以初步准备用于灌溉施肥的土壤。本文表明，在干燥过程中，盐分主要集中在湿度梯度陡峭的区域，即干燥和潮湿土壤之间的边界处。这是因为土壤水分由于压力下降而进入盐浓度已经增加的区域。开发的模型使得可以根据设定的初始和边界条件（水分梯度、孔隙度、土壤比表面积、灌溉强度和持续时间以及盐浓度）来分析盐边形成的影响。